Frost event 4-15-14

We had a fairly hard frost this morning. The low at nearby Opossum Hollow was 25.5.  My measurements on frost events in the vineyard generally come in a bit lower, but I didn't have any instruments out this morning.

Here is what the temps looked like (click to expand):

Sunday night, I counted 14 crosses with developing flowers.  This evening, there were only 3.  Two of the survivors were cinerea crosses. The third looks like is has a cinerea pedigree, but the parents are unknown.

Below is a good example the cinerea style 'frost response'.  It parents were Bridlegate Cinerea and Mourvedre.  Note the surviving inflorescence and swelling bud.  Neither show much damage.  Further up the cane, a number of growth points were completely toasted, but the vine had not entirely budded out and ought to produce a crop.   I didn't notice any swelling bud damage.

Cinerea crosses are the only vines with buds still in the 'swelling' phase.

Bridlegate Cinerea x Mourvedre (click to expand):

The photo demonstrates 2 frost adaptations cinerea seems to exhibit: 1) resilience to sub-freezing surface temperatures, and 2) variation in bud burst timing, producing a sequence of bud-burst dates, insuring late frosts cannot wipe out the vine's ability to produce fruit.

The local cinerea had the least damage.  Paluxy cinerea did better than Chalk Mountain cinerea,  The original Paluxy cinerea was found on the river bank, just half a mile up stream.  The original Chalk Mountain cinerea was found about 20 miles away, on a relatively high mesa.  Both did better than the Red River cinerea that was found near Dennison, about 4 hours north of here.

More typical is the below photo of 'selfed Rougeon'.  This is what happened to the crosses with no local cinerea in their pedigree.  Almost all the leaves have been destoyed.  This vine was loaded with large inflorescence nearing floraison.  Now, there is little left.  Note the uniformity of development.  Bud-burst was very uniform for this cross.  It is very unlikely to produce any fruit this year.

 Selfed Rougeon (click to expand):

Last year, we had a similar experience with selfed Rougeon seedlings.  The vine was loaded with flowers when the May frost event occurred.  That relatively light frost destroyed every blossom, and none emerged later in the year.

Last year, rupestris and bicolor crosses survived the May frost and produced fruit.  Neither survived today's frost. Both had every inflorescence destroyed.